1. Field of the Invention
The present invention generally relates to an air conditioning apparatus for cooling and heating vehicles, such as automobiles.
2. Description of Relevant Art
FIG. 15 is an arrangement view showing a conventional example of air conditioning apparatus for cooling and heating vehicles. In FIG. 15, a casing 1 which in order from an upstream end contains therein air conditioning components such as a fan 2 for feeding air, an evaporator 3, an air mixing damper 5, and a heater 4.
At one end of the casing 1 are provided an inside air suction opening 21 and an outside air suction opening 22 are provided. The openings 21,22 are selectively opened by a switching damper 9 for selectively introducing the air circulating within the compartment and air from the outside. Disposed downstream of the suction openings 21, 22 is the fan 2 directly connected to an electric motor. Disposed within a pressurized air passage 24 downstream of the fan 2 is the evaporator 3 which has a refrigerant or coolant inlet connected to an expansion valve (not shown) via a refrigerant tube and a refrigerant outlet connected to a compressor (not shown) via another refrigerant tube. The heater 4 is disposed within a pressurized air passage 25 downstream of the evaporator 3. The hot water inlet and outlet of the heater 4 are connected via hot water tubes to a cooling water circuit system (not shown) for a vehicular engine.
Disposed within the air passage 25 just upstream of the heater 4 is the air mixing damper 5 which is fixed to a damper driving shaft 10 to be swung therewith. The damper 5 is swingable about the shaft 10 within the air passage 25 upstream of the heater 4, so as to be operable between positions to fully close and fully open the front air receiving side of the heater 4. Thus, there is ensured a space within the air passage 25, for operating the damper 5.
In the operation of the air conditioning apparatus as constructed above, the fan 2 is driven to selectively introduce the air circulating within the compartment through the inside air suction opening 21 or the outside air through the outside air suction opening 22, so as to pressurizingly feed the introduced air to the air passage 24. The pressurized fed air passes through the gaps between the fins of evaporator 3, where it is cooled by heat exchange with the refrigerant flowing in the tubes of the fins, and thereafter reaches the air passage 25. If the air mixing damper 5 is then positioned to fully close the front side of heater 4, the air cooled by the evaporator 3, passes through the passage 25, a pressurized air passage 23 downstream of the heater 4, and a damper (not shown) for switching the modes of blow openings, and is blown as cooled air into the compartment via the blow openings, while by-passing the heater 4.
When the air mixing damper 5 is rotated into the position depicted by a broken line in FIG. 15 to fully open the front side of the heater 4, the air passage 25 is fully closed except for the heater 4, so that the air cooled by evaporator 3 is introduced into the heater 4. The thus introduced air is heated by heat exchange with the hot water flowing in the tube of heater 4, passes through the air passage 23 downstream of heater 4, and through the aforementioned mode switching damper, and is finally blown as hot air into the compartment via the blow openings.
When the air mixing damper 5 is kept in the position between the full opening and closing positions for the front side of heater 4, the air cooled by evaporator 3 partially passes through the heater 4 to be heated into hot air, and the remainder unchangedly by-passes the heater 4. The cooled air and hot air are then mixed with each other within the outlet air passage 23 downstream of heater 4, and the thus mixed air is blown into the compartment via the blow openings in the same manner as above, at an adjusted temperature determined by the mixing ratio. That is, within such a range that the air mixing damper 5 is rotated from the full closing position to the full opening position for the heater 4, the flowing directions of air upstream of heater 4 can be adjusted by the operational angular position of damper 5 to change the mixing ratio of the hot air to the cooled air such that the temperature of mixed air blown into the compartment is adjusted.
However, there exist such problems to be solved in the conventional air conditioning apparatus for vehicles (automobiles) shown in FIG. 15.
Namely, in such a conventional air conditioning apparatus for vehicles, the temperature of air blown into the compartment is adjusted by the angular position of the air mixing damper 5 which is directly connected to the damper driving shaft 10 supported by the casing 1 and swung about the shaft 10 as the rotation axis. This means that a space should be ensured within the casing 1, for accommodating the angular motion of the air mixing damper 5. The provision of such a space for accommodating the swing of damper 5 represents a large restriction in reducing the size of casing 1.
Further, the temperature of air blown into the compartment could not be fully proportioned to the operational angle of damper 5, since the adjustment of mixing ratio of the hot air to the cooled air for adjusting the air temperature at the blow openings is performed by adjusting the air flowing directions within the air passage by changing the swung angle of the air mixing damper 5. Thus, it is also difficult to adjust the temperature of blown air, in the conventional technique. In addition, since the air mixing damper 5 is operated to swing within the pressurized air passage 25, the damper 5 undergoes a dynamic pressure of the passing air, resulting in large fluctuations of the required operational forces for damper 5 depending on its operational angles. Thus, it is difficult to set or determine the operational forces of the damper 5.
Still further, since the driving device for driving the air mixing damper 5 is typically projected outwardly from the casing 1, the space required for installing and operating the driving device is increased in size, thereby preventing a reduction in size and compactness which is most required for vehicles.